More rain forecast for Southern California, along with snow and gusty winds, through weekend

Cars coming off the 110 Freeway make waves at the intersection of Francisco and James Wood near the Staples Center Thursday, Nov 21, 2013 in Los Angeles Calif. The rain caused a storm drain to get clogged and flood the intersection. (Photo by Gene Blevins/Los Angeles Daily News)

A cold upper-level low-pressure system brought the Southland heavy snow and gusty winds into Friday, creating a possibility of highly hazardous whiteout conditions on some major roads in the San Gabriel Mountains and the Antelope Valley, forecasters said.

There also exists a slight chance of thunderstorms, according to the National Weather Service.

In the San Gabriel Mountains in Los Angeles County, a winter storm warning denoting severe winter weather conditions is scheduled to be in effect until noon today.

The snow level will be between 4,000 and 5,000 feet in the San Gabriels, and snow accumulation of between 6 and 12 inches is expected, though it could be up to 15 inches along interior slopes, where the snow level will be down to 3,000 feet, according to an NWS advisory.

At the same time, the San Gabriels will be swept by northeast winds of between 25 and 35 miles per hour, gusting to up to 55 mph, especially over ridges and through passes and canyons.

``The combination of strong winds and snow will result in dangerous driving conditions due to blowing and drifting snow and near-zero visibilities at times,’’ the advisory cautioned. ``Portions of Angeles Crest Highway ... and surrounding roads will be most vulnerable to these conditions.’’

In the Antelope Valley, a winter weather advisory heralding snow and blowing snow will be in force until noon today while in the Ventura County portion of the San Gabriels the advisory will expire at 4 p.m. Friday.

Snow measuring 3 to 6 inches was expected in the Antelope Valley foothills above 3,000 feet, especially near Littlerock and Llano, according to NWS forecasters, who warned of northeast wins of between 15 and 25 mph, gusting to 40 mph.

Forecasters warned of the possibility of near-zero visibility at times on Pearblossom Highway because of the combination of falling snow and high winds. Also threatened are Highway 33 and Lockwood Valley Road in Ventura County.

An urban-and-small-stream advisory that was in force in the mountain and the Antelope Valley Thursday night has been allowed to expire, forecasters said, but ponding in low-lying areas and some roadway flooding remained possible.

In areas where no snow was expected, a wind advisory will be in force until noon Saturday in the Santa Monica Mountains Recreational Area and the San Fernando and Santa Clarita valleys, authorities said.